The present invention relates generally to the cooling of electronic components, and particularly to the use of fans for cooling electronic components.
The cooling of electronic components such as high power density devices, (HPDDs) including high power density integrated circuits (IC's) and central processing units (CPU's) for example, is a significant consideration in the design of computer servers, military avionic equipment, medical imaging equipment, and other systems employing high power density electronic devices. The term HPDD used herein refers to heat generating devices having a heat flux in excess of 10 Watts-per-square-centimeter. In addition to having variations in heat flux, HPDDs have various peak permissible temperatures which also affect cooling requirements Electronic systems are being designed with for greater computational speed and power and smaller footprints. These design goals result in a HPDD that generates a lot of heat in a small area/volume. Heat dissipation is important in order to avoid IC and CPU degradation. Power densities of some electronic systems are as high as about 200 watts per square centimeter (W/sq-cm), and the trend appears to be moving upward. In addition to heat dissipation requirements that result from heat generation, enclosure size constraints present design challenges. For example, conventional computer servers typically employ circuit boards that are housed in enclosures with a height restriction of 1.75 inches, referred to as a 1U application, with multiple circuit boards being stacked adjacent one another in a rack chassis. With a typical electronic component having an ambient use temperature of no greater than about 120 degree-Celsius (deg-C.) and a junction temperature restriction of about 90 deg-C., cooling systems are employed to transfer the heat of the HPDD to the surrounding ambient. Typical cooling systems include fans, blowers, heat sinks, and refrigeration systems, which tend to increase in size as the heat transfer demands increase.
Accordingly there is a need for an efficient thermal management for electronic components including high power density devices.